The field of the invention generally pertains to fasteners. The invention relates more particularly to a nut with a coaxial bearing for dynamically brace-supporting a pair of coaxial cylindrical surfaces rotating independently of the other. A typical application of the nut is to dynamically brace-support a main drive gear to a coaxial mainshaft of a Harley-Davidson motorcycle transmission.
Nuts are commonly used to secure a bolt or similarly threaded shank to an attaching piece. In one particular application, a nut is used in Harley-Davidson motorcycle transmissions to secure a final-drive transmission pulley or sprocket (belt or chain drive, respectively) to a main drive gear with a threaded end partially protruding out from inside the transmission case. The main drive gear has a cylindrically hollow center permitting a mainshaft to coaxially extend therethrough and into the transmission case. When in operation, the mainshaft functions to transfer power into the transmission, while the main drive gear functions to transfer power to the rear wheel via the final-drive transmission pulley or sprocket.
One common problem with earlier model Harley-Davidson motorcycles, however, is transmission oil leakage through the main drive gear at the final drive transmission pulley or sprocket. The leakage is caused by wear of the main drive gear bushing and seal located inside the cylindrically hollow center of the main drive gear. Wear on the main drive gear bushing and seal occurs when the mainshaft and/or the main drive gear experiences axial deviation relative to the other during operation, i.e. the main drive gear and/or mainshaft deviates from their common central axis of rotation. This typically occurs due to lack of support of the main drive gear and/or mainshaft in the transmission. The resulting leakage can be messy and frustrating to clean up, and can detract from the enjoyment of riding and owning a Harley-Davidson motorcycle.
One type of nut currently in use incorporates a seal on an abutment surface of the nut in an attempt to remedy the transmission oil leakage problem for Harley-Davidson motorcycles. The nut is threadedly mounted on the main drive gear following the mounting of a final-drive transmission pulley or sprocket on the main drive gear. The nut abuts against the final-drive transmission pulley or sprocket along the seal and secures it to the main drive gear. This prior art nut, however, does not address or correct the source of the problem, i.e. wear in the main drive gear bushing and seal caused by deviation of the main drive gear and/or mainshaft from its true axis of rotation. Oil still seeps through the bushing and seal and out of the transmission case because the main drive gear remains unsupported.